This is counter to what the tutorial seems to outline. Selecting vertices in the options appears to convert the sub-d's back to the original mesh density, unsuitable for rendering.
Am I to understand by this that in general, car models with enough detail for final rendering in Maya will always be in the 20-50MB range. That seems a bit excessive. My experiences with other apps (eg. LW and Modo) seem much more efficient. I'm not knocking Maya, I'm just trying to understand, If I'm missing something I seriously want to know.